This is what I was able to find about
Guerre a la Terre. Sources include Wikipedia France, Bedetheque, an online biography of Marijac emphasizing his
Coq Hardi period, Lambiek, and several collector / sales sites.
The story appeared as a serial in the weekly
Coq Hardi beginning in 1946. The series comprised two parts. Part one, 60 pages, ran in issues #10 through #69. It was drawn by Auguste Liquois. Part two, 37 pages, ran from #85 to #121. It was drawn by "Dut" (Pierre Duteurte). Both parts were written by Marijac (Jacques Dumas), a co-founder of
Coq Hardi.When it came out that Liquois had collaborated with Nazi magazines during the war, drawing propaganda material, Marijac (who'd worked in the Resistance) canned him. Duteurte was chosen to continue
Alerte a Terre in his stead. This didn't seem to hurt Liquois' career, though. He remained active in French comics up until his death in 1969.
Here's the cover of
Coq Hardi #42, 9 January 1947:
Based on this material I must conclude that the 1945 date for the Spanish reprint series is in error. 1946 is more likely.